package com.example.informationEntry.util;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.io.IOUtils;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;


/**
 * @version v1.0
 * @ProjectName: ThreeNewBoard
 * @ClassName: RSAUtils
 * @Description: TODO(RSA加解密 ， 输出公钥私钥)
 * @Author: sunbo@pgytesting.cn
 * @Date: 2019/1/23 17:36
 */
public class RSAUtils {
    public static final String CHARSET = "UTF-8";
    public static final String RSA_ALGORITHM = "RSA";


    /**
     * BASE64解密
     *
     * @param key
     * @return
             * @throws Exception
     */
    public static byte[] decryptBASE64(String key) throws Exception {
        return (new BASE64Decoder()).decodeBuffer(key);
    }

    /**
     * BASE64加密
     *
     * @param key
     * @return
     * @throws Exception
     */
    public static String encryptBASE64(byte[] key) throws Exception {
        return (new BASE64Encoder()).encodeBuffer(key);
    }


    public static Map<String, String> createKeys() throws Exception {

        //为RSA算法创建一个KeyPairGenerator对象
        KeyPairGenerator kpg;
        try {
            kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");
        }
        //初始化KeyPairGenerator对象,密钥长度
        kpg.initialize(1024, new SecureRandom());
        //生成密匙对
        KeyPair keyPair = kpg.generateKeyPair();
        //得到公钥
        String publicKeyStr = encryptBASE64(keyPair.getPublic().getEncoded());
        //得到私钥
        String privateKeyStr = encryptBASE64(keyPair.getPrivate().getEncoded());

        Map<String, String> keyPairMap = new HashMap<>();
        keyPairMap.put("publicKey", publicKeyStr.replaceAll("(\r\n|\r|\n|\n\r)", ""));
        keyPairMap.put("privateKey", privateKeyStr.replaceAll("(\r\n|\r|\n|\n\r)", ""));

        return keyPairMap;

    }


    /**
     * 得到公钥
     *
     * @param publicKey 密钥字符串（经过base64编码）
     * @throws Exception
     */
    public static RSAPublicKey getPublicKey(String publicKey) throws Exception {
        //通过X509编码的Key指令获得公钥对象
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(decryptBASE64(publicKey));
        RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
        return key;
    }

    /**
     * 得到私钥
     *
     * @param privateKey 密钥字符串（经过base64编码）
     * @throws Exception
     */
    public static RSAPrivateKey getPrivateKey(String privateKey) throws Exception {
        //通过PKCS#8编码的Key指令获得私钥对象
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(decryptBASE64(privateKey));
        RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
        return key;

    }


    /**
     * 公钥加密
     *
     * @param data
     * @param publicKey
     * @return
     */
    public static String publicEncrypt(String data, RSAPublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()));
        } catch (Exception e) {
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }


    /**
     * 私钥解密
     *
     * @param data
     * @param privateKey
     * @return
     */

    public static String privateDecrypt(String data, RSAPrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), CHARSET);
        } catch (Exception e) {
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥加密
     *
     * @param data
     * @param privateKey
     * @return
     */
    public static String privateEncrypt(String data, RSAPrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()));
        } catch (Exception e) {
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 公钥解密
     *
     * @param data
     * @param publicKey
     * @return
     */

    public static String publicDecrypt(String data, RSAPublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), publicKey.getModulus().bitLength()), CHARSET);
        } catch (Exception e) {
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize) {
        int maxBlock = 0;
        if (opmode == Cipher.DECRYPT_MODE) {
            maxBlock = keySize / 8;
        } else {
            maxBlock = keySize / 8 - 11;
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] buff;
        int i = 0;
        try {
            while (datas.length > offSet) {
                if (datas.length - offSet > maxBlock) {
                    buff = cipher.doFinal(datas, offSet, maxBlock);
                } else {
                    buff = cipher.doFinal(datas, offSet, datas.length - offSet);
                }
                out.write(buff, 0, buff.length);
                i++;
                offSet = i * maxBlock;
            }
        } catch (Exception e) {
            throw new RuntimeException("加解密阀值为[" + maxBlock + "]的数据时发生异常", e);
        }
        byte[] resultDatas = out.toByteArray();
        IOUtils.closeQuietly(out);
        return resultDatas;
    }


    public static void main(String[] args) throws Exception {
        Map<String, String> keyMap = RSAUtils.createKeys();//replaceAll("(\\\\r\\\\n|\\\\r|\\\\n|\\\\n\\\\r)", "<br />");
        String publicKey = keyMap.get("publicKey");
        String privateKey = keyMap.get("privateKey");
//        String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCUgOUdAfgrsnSq+l96i20wDJQuTogaIi63ktoK\n" +
//                "RpsP7lfNx8TwPuBisI3g43FFdTqB5NWhAWIlvQ53Z8Xmnw3QzAEdU55oq84akky2HUT2rF0RrDWq\n" +
//                "JNKLC4GRywe/i2jSeFP0s4Qvds6hatAZOpmNmPvK953xKetcLXMsv0gkEQIDAQAB";
//        String privateKey = "MIICdwIBADANBgkqhkiG9w0BAQEFAASCAmEwggJdAgEAAoGBAJSA5R0B+CuydKr6X3qLbTAMlC5O\n" +
//                "iBoiLreS2gpGmw/uV83HxPA+4GKwjeDjcUV1OoHk1aEBYiW9DndnxeafDdDMAR1TnmirzhqSTLYd\n" +
//                "RPasXRGsNaok0osLgZHLB7+LaNJ4U/SzhC92zqFq0Bk6mY2Y+8r3nfEp61wtcyy/SCQRAgMBAAEC\n" +
//                "gYAPBMonGN/ka3PpJtEpL5inV15VIJQbMIHRBwUOLP3Zqp0urpl4QqOm13xB1j7Ka4SzRlVkpyMp\n" +
//                "9ejUoqYdINDguXrBNkHWc5tLC/+CY7WAlZ1quUePrfI+NEVLIzWrxQoIB5AwcVz+e6lVesP3IJOd\n" +
//                "a9r78qvUAmvrtBZd/UjdAQJBANBMpeslO8M8BIKD4zKDMo4UqepjR2u1t1MGvLb4dfUZ/xvSDzGz\n" +
//                "xawFOkl9d8VJcXAc+/sFRbzeEKXmpD7OHRkCQQC2gsTtEVOhlu104XN3+HJE++qqZ5eApbRqUv7F\n" +
//                "2n09GBe91NxU9GqxnGaCItF8UFeBsJ8u+IIWsPqSv0g+tKW5AkA7vX/ojOky+Ueh1wmWNyKMtUh2\n" +
//                "PLsDHT7SxR/iqifKgAY2iGxrKNAMogMxiJaNMp8iNG3gdIanwFit/BQnHx4hAkEAlgAeJ5Vw/cLU\n" +
//                "wJY216g7ClVdhdYEH3iRMj2qJSSwf9DYWm2i9LO5KOaZHWXOdHR3pyBphCo8iLfGCWvqzZadCQJB\n" +
//                "AMZnbi2LgENp9ht298LwMLF1Hei2tGh2Cv/GVu58JTQ8DyawaObcyytaktwYD69Y43yqdI9WbvQI\n" +
//                "xPXoOf524+M=";
        System.out.println("公钥: \n\r" + publicKey);
        System.out.println("私钥： \n\r" + privateKey);
        System.out.println("公钥加密——私钥解密");
        String str = "admin@123";
        System.out.println("\r明文：\r\n" + str);
        System.out.println("\r明文大小：\r\n" + str.getBytes().length);
//        String str = "admin@123";
//        String publicKey = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAK2e1QAKO1vZUox-tuRfuXMW2a3TawhDlXIXCHHpdmyoP_GYTG430xfAYvpkY1Xyr_Ic4cUHyJ9QwTMaQ_Bwx1ECAwEAAQ";
        String encodedData = RSAUtils.publicEncrypt(str, RSAUtils.getPublicKey(publicKey));
//        String encodedData = "g+jwYX2LGyAJPsy6xMGK9DGCLC65yfuowJse6uR1M1D/easN3UZWgACRZQncpkXGh5dZ1bIFcRT/x5Ow0l+dPkbwdGctMVXhQ/BzMiRJ4a890SwZ4L78c14cejgB0d266w766ZulnySZKOi5HTKNAo5p1Z7mb2e/dLBCYLyLwYU=";
        System.out.println("密文：\r\n" + encodedData);
        String decodedData = RSAUtils.privateDecrypt(encodedData, RSAUtils.getPrivateKey(privateKey));
        System.out.println("解密后文字: \r\n" + decodedData);


    }


}